Authors: Charles R. O'Dell Extension Horticulturist, Department of Horticulture, Virginia Tech; Jerry Williams, Teaching Hortculturist, Department of Horticulture, Virginia Tech
Publication Number 438-018, Posted March 2000
TABLE 8 - Weekly Spring 1994 Petiole Sap Levels in PPM of Fresh Plant Sap for Nitrogen and Potash1, April 1 - June 10, cv Chandler Strawberries, Kentland Research Farm, Va Tech, Blacksburg, Va.
| N03-N1 (Ideal Range)2 | K20 (Ideal Range) | |
|---|---|---|
| 4/01 | 540 (600-800) | 2500 (3000+ 1st blooms visible) |
| 4/08 | 500 (300-500) | 2400 (2500+) |
| 4/15 | 450 (300-500) | 2400 (2500+) |
| 4/22 | 248 (200+) | 2400 (2500+ 1st fruit visible) |
| 4/29 | 250 (200+) | 2300 (2500+) |
| 5/06 | 217 (200+) | 2300 (2000+) |
| 5/13 | 215 (200+) | 2200 (2000+ 1st fruit pinking) |
| 5/20 | 200 (200+) | 1900 (1800+ 1st harvests) |
| 5/27 | 200 (200+) | 1900 (1800+ harvesting) |
| 6/3 | 190 (200+) | 1800 (1500+ harvesting) |
| 6/10 | 190 (200+) | 1800 (1500+ harvesting) |
1 From in-field readings made with portable Cardy N and K Ion Meters, from Spectrum Technologies, Inc., 12010, So. Aero Drive, Plainfield, IL 60544.
2 From George Hochmuth, 1993. Grower Guidelines: Hard Figures For Petiole Sap Testing, American Vegetable Grower, Meister Pub. Co., Willoughby, OH 44094, Vol. 41, No. 12, Dec., 1993, pp. 62-63.Research has found no yield or quality increase from using phosphate and/or potash with nitrogen fertigated weekly in the spring, provided that phosphate and potash levels were brought to the high range by pre-plant field additions based on soil test report.
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